Integrated circuit for response signal spreading

ABSTRACT

A wireless communication apparatus capable of minimizing the degradation of the separation characteristic of response signals to be code-multiplexed. In the apparatus, a control part ( 209 ) controls both a ZC sequence to be used for the primary spread in a spreading part ( 214 ) and a Walsh sequence to be used for the secondary spread in a spreading part ( 217 ) according to the associations between sequences and CCEs established in accordance with the probability of using response signal physical-resources corresponding to CCE numbers. The spreading part ( 214 ) performs the primary spread of the response signal by use of the ZC sequence established by the control part ( 209 ). The spreading part ( 217 ) performs the secondary spread of the response signal, to which CP has been added, by use of the Walsh sequence established by the control part ( 209 ).

TECHNICAL FIELD

The present invention relates to a radio communication apparatus andresponse signal spreading method.

BACKGROUND ART

In mobile communication, ARQ (Automatic Repeat Request) is applied todownlink data from a radio communication base station apparatus(hereinafter abbreviated to “base station”) to radio communicationmobile station apparatuses (hereinafter abbreviated to “mobilestations”). That is, mobile stations feed back response signalsrepresenting error detection results of downlink data, to the basestation. Mobile stations perform a CRC (Cyclic Redundancy Check) ofdownlink data, and, if CRC=OK (no error), feed back an ACK(ACKnowledgement), and, if CRC=NG (error present), feed back a NACK(Negative ACKnowledgement), as a response signal to the base station.These response signals are transmitted to the base station using uplinkcontrol channels such as a PUCCH (Physical Uplink Control CHannel).

Also, the base station transmits control information for reportingresource allocation results of downlink data, to the mobile stations.This control information is transmitted to the mobile stations usingdownlink control channels such as L1/L2 CCH's (L1/L2 Control CHannels).Each L1/L2 CCH occupies one or a plurality of CCE's. If one L1/L2 CCHoccupies a plurality of CCE's (Control Channel Elements), the pluralityof CCE's occupied by the L1/L2 CCH are consecutive. Based on the numberof CCE's required to carry control information, the base stationallocates an arbitrary L1/L2 CCH among the plurality of L1/L2 CCH's toeach mobile station, maps control information on the physical resourcesassociated with the CCE's (Control Channel Elements) occupied by theL1/L2 CCH, and performs transmission.

Also, to use downlink communication resources efficiently, studies areunderway to associate PUCCH's with CCE's on a one-to-one basis.According to this association, each mobile station can decide the PUCCHto use to transmit a response signal from that mobile station, from theCCE corresponding to physical resources on which control information forthat mobile station is mapped. That is, each mobile station maps aresponse signal from the subject mobile station on a physical resource,based on the CCE corresponding to physical resources on which controlinformation for that mobile station is mapped.

Also, as shown in FIG. 1, studies are underway to performcode-multiplexing by spreading a plurality of response signals from aplurality of mobile stations using ZC (Zadoff-Chu) sequences and Walshsequences (see Non-Patent Document 1). In FIG. 1, (W₀, W₁, W₂, W₃)represents a Walsh sequence having a sequence length of 4. As shown inFIG. 1, in a mobile station, first, an ACK or NACK response signal issubject to first spreading to one symbol by a ZC sequence (having asequence length of 12) in the frequency domain. Next, the responsesignal subjected to first spreading is subject to an IFFT (Inverse FastFourier Transform) in association with W₀ to W₃. The response signalspread in the frequency domain by a ZC sequence having a sequence lengthof 12 is transformed to a ZC sequence having a sequence length of 12 bythis IFFT in the time domain. Then, the signal subjected to the IFFT issubject to second spreading using a Walsh sequence (having a sequencelength of 4). That is, one response signal is allocated to each of foursymbols S₀ to S₃. Similarly, response signals of other mobile stationsare spread using ZC sequences and Walsh sequences. Here, differentmobile stations use ZC sequences of different cyclic shift values in thetime domain or different Walsh sequence. Here, the sequence length of ZCsequences in the time domain is 12, so that it is possible to use twelveZC sequences of the cyclic shift values “0” to “11,” generated from thesame ZC sequence. Also, the sequence length of Walsh sequences is 4, sothat it is possible to use four different Walsh sequences. Therefore, inan ideal communication environment, it is possible to code-multiplexmaximum forty-eight (12×4) response signals from mobile stations.

Here, there is no cross-correlation between ZC sequences of differentcyclic shift values generated from the same ZC sequence. Therefore, inan ideal communication environment, a plurality of response signalssubjected to spreading and code-multiplexing by ZC sequences ofdifferent cyclic shift values (0 to 11), can be separated in the timedomain without inter-code interference, by correlation processing in thebase station.

However, due to the influence of, for example, transmission timingdifference in mobile stations, multipath delayed waves and frequencyoffsets, a plurality of response signals from a plurality of mobilestations do not always arrive at a base station at the same time. Forexample, if the transmission timing of a response signal spread by a ZCsequence of the cyclic shift value “0” is delayed from the correcttransmission timing, the correlation peak of the ZC sequence of thecyclic shift value “0” may appear in the detection window for the ZCsequence of the cyclic shift value “1.” Further, if a response signalspread by the ZC sequence of the cyclic shift value “0” has a delaywave, interference leakage due to the delayed wave may appear in thedetection window for the ZC sequence of the cyclic shift value “1.” Thatis, in these cases, the ZC sequence of the cyclic shift value “1” isinterfered by the ZC sequence of the cyclic shift value “0.” Therefore,in these cases, the separation performance degrades in a response signalspread by the ZC sequence of the cyclic shift value “0” and a responsesignal spread by the ZC sequence of the cyclic shift value “1.” That is,if ZC sequences of adjacent cyclic shift values are used, the separationperformance of response signals may degrade.

Therefore, up till now, if a plurality of response signals arecode-multiplexed by spreading using ZC sequences, a difference of cyclicshift values (i.e. a cyclic shift interval) is provided between the ZCsequences, to an extent that does not cause inter-code interferencebetween the ZC sequences. For example, when the difference between thecyclic shift values of ZC sequences is 2, only six ZC sequences of thecyclic shift values “0,” “2” “4,” “6,” “8” and “10” amongst twelve ZCsequences of the cyclic shift values “0” to “11,” are used in firstspreading of response signals. Therefore, if Walsh sequences having asequence length of 4 are used in second spreading of response signals,it is possible to code-multiplex maximum 24 (6×4) response signals frommobile stations.

Non-Patent Document 1: Multiplexing capability of CQIs and ACK/NACKsform different UEs(ftp://ftp.3gpp.org/TSG_RAN/WG1_RL1/TSGR1_(—)49/Docs/R1-072315.zip)

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

As described above, if a Walsh sequence having a sequence length of 4,(W₀, W₁, W₂, W₃), is used in second spreading, one response signal isallocated to each of four symbols (S₀ to S₃). Therefore, a base stationthat receives response signals from mobile stations needs to despreadthe response signals over a time period of four-symbols. On the otherhand, if a mobile station moves fast, there is a high possibility thatthe channel conditions between the mobile station and the base stationvary during the above four-symbol time period. Therefore, when there isa mobile station moving fast, the orthogonality between the Walshsequences used in second spreading may collapse. That is, when there isa mobile station moving fast, inter-code interference is more likely tooccur between Walsh sequences than between ZC sequences, and, as aresult, the separation performance of response signals degrades.

By the way, when some of a plurality of mobile stations move fast andthe rest of the mobile stations are in a stationary state, the mobilestations in a stationary state, which are multiplexed with the mobilestations moving fast on the Walsh axis, are also influenced byinter-code interference.

It is therefore an object of the present invention to provide a radiocommunication apparatus and response signal spreading method that canminimize the degradation of the separation performance of responsesignals that are code-multiplexed.

Means for Solving the Problem

The radio communication apparatus of the present invention employs aconfiguration having: a first spreading section that performs firstspreading of a response signal using one of a plurality of firstsequences that can be separated from each other because of differentcyclic shift values; and a second spreading section that performs secondspreading of the response signal subjected to the first spreading, usingone of a plurality of second sequences, and in which the first spreadingsection and the second spreading section perform the first spreading andthe second spreading of the response signal, using the one of theplurality of first sequences and the one of the plurality of secondsequences, the first sequences and the second sequences being associatedwith control channel elements based on a use probability of physicalresources for response signals associated with control channel elementnumbers.

Advantageous Effect of Invention

According to the present invention, it is possible to minimize thedegradation of the separation performance of response signals that arecode-multiplexed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a spreading method of response signals(prior art);

FIG. 2 is a block diagram showing the configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 3 is a block diagram showing the configuration of a mobile stationaccording to Embodiment of the present invention;

FIG. 4 illustrates associations of ZC sequences and Walsh sequences withPUCCH's according to Embodiment 1 of the present invention;

FIG. 5 illustrates associations of ZC sequences and Walsh sequences withCCE's according to Embodiment 1 of the present invention;

FIG. 6 illustrates mappings between L1/L2 CCH's and CCE's according toEmbodiment 1 of the present invention;

FIG. 7 illustrates mappings between L1/L2 CCH's and CCE's according toEmbodiment 2 of the present invention;

FIG. 8 illustrates associations of ZC sequences and Walsh sequences withCCE's according to Embodiment 2 of the present invention;

FIG. 9 illustrates associations of ZC sequences and Walsh sequences withCCE's according to Embodiment 3 of the present invention;

FIG. 10 illustrates mappings between L1/L2 CCH's and CCE's according toEmbodiment 4 of the present invention (variation 1);

FIG. 11 illustrates mappings between L1/L2 CCH's and CCE's according toEmbodiment 4 of the present invention (variation 2);

FIG. 12 illustrates associations of ZC sequences and Walsh sequenceswith CCE's according to Embodiment 4 of the present invention;

FIG. 13 illustrates associations of ZC sequences and Walsh sequenceswith CCE's according to Embodiment 5 of the present invention (variation1);

FIG. 14 illustrates associations of ZC sequences and Walsh sequenceswith CCE's according to Embodiment 5 of the present invention (variation2);

FIG. 15 illustrates associations of ZC sequences and Walsh sequenceswith CCE's according to Embodiment 6 of the present invention; and

FIG. 16 illustrates a spreading method of a reference signal.

BEST MODE FOR CARRYING OUT INVENTION

Embodiments of the present invention will be explained below in detailwith reference to the accompanying drawings.

FIG. 2 illustrates the configuration of base station 100 according tothe present embodiment, and FIG. 3 illustrates the configuration ofmobile station 200 according to the present embodiment.

Here, to avoid complicated explanation, FIG. 2 illustrates componentsassociated with transmission of downlink data and components associatedwith reception of uplink response signals to the downlink data, whichare closely related to the present invention, and the illustration andexplanation of the components associated with reception of uplink datawill be omitted. Similarly, FIG. 3 illustrates components associatedwith reception of downlink data and components associated withtransmission of uplink response signals to the downlink data, which areclosely related to the present invention, and the illustration andexplanation of the components associated with transmission of uplinkdata will be omitted.

Also, in the following explanation, a case will be described where ZCsequences are used in first spreading and Walsh sequences are used insecond spreading. Here, for the first spreading, it is equally possibleto use sequences that are separable from each other because of differentcyclic shift values, other than ZC sequences. Similarly, for secondspreading, it is equally possible to use orthogonal sequences other thanWalsh sequences.

Further, in the following explanation, a case will be described where aZC sequence having a sequence length of 12 and a Walsh sequence having asequence length of 4 (W₀, W₁, W₂, W₃) are used. However, the presentinvention is not limited to these sequence lengths.

Further, in the following explanation, twelve ZC sequences of the cyclicshift values “0” to “11” will be referred to as “ZC #0” to “ZC #11,” andfour Walsh sequences of sequence numbers “0” to “3” will be referred toas “W #0” to “W #3.”

Further, a case will be described with the following explanation wherethree Walsh sequences, W #0 to W #2, are used among Walsh sequences W #0to W #3.

Also, as shown in FIG. 4, the PUCCH numbers are defined by the cyclicshift values of ZC sequences and Walsh sequence numbers. The followingexplanation assumes that the PUCCH numbers are associated with the CCEnumbers on a one-to-one basis.

In base station 100 shown in FIG. 2, control information generatingsection 101 and mapping section 104 receive as input a resourceallocation result of downlink data.

Control information generating section 101 generates control informationper mobile station to carry the resource allocation result, and outputsthe control information to encoding section 102. Control information,which is provided per mobile station, includes mobile station IDinformation to indicate to which mobile station the control informationis directed. For example, control information includes, as mobilestation ID information, a CRC masked by the ID number of the mobilestation to which control information is carried. Control information isencoded in encoding section 102, modulated in modulating section 103 andreceived as input in mapping section 104, on a per mobile station basis.Further, control information generating section 101 allocates an L1/L2CCH to each mobile station, based on the number of CCE's required tocarry control information (i.e. the number of CCE's occupied), andoutputs the CCE number corresponding to the allocated L1/L2 CCH tomapping section 104.

In the following, the coding rate of an L1/L2 CCH is one of 2/3, 1/3 and1/6, and an L1/L2 CCH of the coding rate 2/3 occupies one CCE.Therefore, an L1/L2 CCH of the coding rate 1/3 occupies two CCE's, andan L1/L2 CCH of the coding rate 1/6 occupies four CCE's. For example, ifmobile station 200 is located far from base station 100 and has lowerreceived quality, an L1/L2 CCH in encoding section 102 has a lowercoding rate, and, consequently, the number of CCE's increases. Bycontrast, if mobile station 200 is located near base station 100 and hashigher received quality, an L1/L2 CCH in encoding section 102 has ahigher coding rate, and, consequently, the number of CCE's decreases.That is, an L1/L2 CCH of a lower coding rate occupies a larger number ofCCE's, and an L1/L2 CCH of a higher coding rate occupies a smallernumber of CCE's. In other words, mobile station 200 to which an L1/L2 ofa low coding rate is allocated has a large number of CCE's, and mobilestation 200 to which an L1/L2 of a high coding rate is allocated has asmall number of CCE's

Also, a control information generation in control information generatingsection 101 will be described later in detail.

On the other hand, encoding section 105 encodes transmission data foreach mobile station (i.e. downlink data) and outputs the encodedtransmission data to retransmission control section 106.

Upon initial transmission, retransmission control section 106 holds theencoded transmission data on a per mobile station basis, and outputs thedata to modulating section 107. Retransmission control section 106 holdstransmission data until retransmission control section 106 receives asinput an ACK of each mobile station from deciding section 116. Further,upon receiving as input a NACK of each mobile station from decidingsection 116, that is, upon retransmission, retransmission controlsection 106 outputs the transmission data corresponding to that NACK tomodulating section 107.

Modulating section 107 modulates the encoded transmission data receivedas input from retransmission control section 106, and outputs the resultto mapping section 104.

Upon transmission of control information, mapping section 104 maps thecontrol information received as input from modulating section 103 on aphysical resource based on the CCE number received as input from controlinformation generating section 101, and outputs the result to IFFTsection 108. That is, mapping section 104 maps control information onthe subcarrier corresponding to the CCE number in a plurality ofsubcarriers comprised of an OFDM symbol, on a per mobile station basis.

On the other hand, upon transmission of downlink data, mapping section104 maps the transmission data per mobile station on a physical resourcebased on the resource allocation result, and outputs the result to IFFTsection 108. That is, based on the resource allocation result, mappingsection 104 maps transmission data on a subcarrier in a plurality ofsubcarriers comprised of an OFDM symbol, on a per mobile station basis.

IFFT section 108 generates an OFDM symbol by performing an IFFT of aplurality of subcarriers on which control information or transmissiondata is mapped, and outputs the OFDM symbol to CP (Cyclic Prefix)attaching section 109.

CP attaching section 109 attaches the same signal as the signal at thetail end part of the OFDM symbol, to the head of the OFDM symbol, as aCP.

Radio transmitting section 110 performs transmission processing such asD/A conversion, amplification and up-conversion on the OFDM symbol witha CP, and transmits the result from antenna 111 to mobile station 200(in FIG. 3).

On the other hand, radio receiving section 112 receives a responsesignal transmitted from mobile station 200, via antenna 111, andperforms receiving processing such as down-conversion and A/D conversionon the response signal.

CP removing section 113 removes the CP attached to the response signalsubjected to receiving processing.

Despreading section 114 despreads the response signal by the Walshsequence that is used in second spreading in mobile station 200, andoutputs the despread response signal to correlation processing section115.

Correlation processing section 115 finds the correlation value betweenthe response signal received as input from dispreading section 114, thatis, the response signal spread by a ZC sequence, and the ZC sequencethat is used in first spreading in mobile station 200, and outputs thecorrelation value to deciding section 116.

Deciding section 116 detects a correlation peak on a per mobile stationbasis, using a detection window set per mobile station in the timedomain, thereby detecting a response signal on a per mobile stationbasis. For example, upon detecting a correlation peak in detectionwindow #1 for mobile station #1, deciding section 116 detects theresponse signal from mobile station #1. Deciding section 116 thendecides whether the detected response signal is an ACK or NACK, andoutputs the ACK or NACK to retransmission control section 106, on a permobile station basis.

On the other hand, in mobile station 200 shown in FIG. 3, radioreceiving section 202 receives an OFDM symbol transmitted from basestation 100, via antenna 201, and performs receiving processing such asdown-conversion and A/D conversion on the OFDM symbol.

CP removing section 203 removes the CP attached to the OFDM symbolsubjected to receiving processing.

FFT (Fast Fourier Transform) section 204 acquires control information ordownlink data mapped on a plurality of subcarriers by performing an FFTof the OFDM symbol, and outputs the control information or downlink datato extracting section 205.

Upon receiving the control information, extracting section 205 extractsthe control information from the plurality of subcarriers and outputs itto demodulating section 206. This control information is demodulated indemodulating section 206, decoded in decoding section 207 and receivedas input in deciding section 208.

On the other hand, upon receiving downlink data, extracting section 205extracts the downlink data directed to the subject mobile station fromthe plurality of subcarriers, based on the resource allocation resultreceived as input from deciding section 208, and outputs the downlinkdata to demodulating section 210. This downlink data is demodulated indemodulating section 210, decoded in decoding section 211 and receivedas input in CRC section 212.

CRC section 212 performs an error detection of the decoded downlink datausing a CRC, generates an ACK in the case of CRC=OK (no error) and aNACK in the case of CRC=NG (error present), as a response signal, andoutputs the generated response signal to modulating section 213.Further, in the case of CRC=OK (no error), CRC section 212 outputs thedecoded downlink data as received data.

Deciding section 208 performs a blind detection of whether or not thecontrol information received as input from decoding section 207 isdirected to the subject mobile station. For example, deciding section208 decides that, if CRC=OK (no error) as a result of demasking by theID number of the subject mobile station, control information is directedto that mobile station. Further, deciding section 208 outputs thecontrol information directed to the subject mobile station, that is, theresource allocation result of downlink data for that mobile station, toextracting section 205. Further, deciding section 208 decides a PUCCH touse to transmit a response signal from the subject mobile station, basedon the CCE number corresponding to a subcarrier on which the controlinformation directed to that mobile station is mapped, and outputs thedecision result (i.e. PUCCH number) to control section 209. For example,if the CCE corresponding to a subcarrier on which control informationdirected to the subject mobile station is mapped is CCE #1, decidingsection 208 decides the PUCCH associated with CCE #1 as the PUCCH forthat mobile station. Also, for example, if the CCE's corresponding tosubcarriers on which control information directed to the subject mobilestation is mapped are CCE #4 and CCE #5, deciding section 208 decidesthat the PUCCH associated with CCE #4, which is the minimum numberbetween CCE #4 and CCE #5, is the PUCCH for that mobile station. Also,for example, if the CCE's corresponding to subcarriers on which controlinformation directed to the subject mobile station is mapped are CCE #8to CCE #11, deciding section 208 decides that the PUCCH associated withCCE #8, which is the minimum number among CCE #8 to CCE #11, is thePUCCH for that mobile station.

Based on the PUCCH number received as input from deciding section 208,control section 209 controls the cyclic shift value of a ZC sequencethat is used in first spreading in spreading section 214 and a Walshsequence that is used in second spreading in spreading section 217. Thatis, control section 209 sets a ZC sequence of the cyclic shift valueassociated with the PUCCH number received as input from deciding section208, in spreading section 214, and sets the Walsh sequence associatedwith the PUCCH number received as input from deciding section 208, inspreading section 217. The sequence control in control section 209 willbe described later in detail.

Modulating section 213 modulates the response signal received as inputfrom CRC section 212 and outputs the result to spreading section 214.

As shown in FIG. 1, spreading section 214 performs first spreading ofthe response signal by the ZC sequence set in control section 209, andoutputs the response signal subjected to first spreading to IFFT section215.

As shown in FIG. 1, IFFT section 215 performs an IFFT of the responsesignal subjected to first spreading, and outputs the response signalsubjected to an IFFT to CP attaching section 216.

CP attaching section 216 attaches the same signal as the tail end partof the response signal subjected to an IFFT, to the head of the responsesignal as a CP.

As shown in FIG. 1, spreading section 217 performs second spreading ofthe response signal with a CP by the Walsh sequence set in controlsection 209, and outputs the response signal subjected to secondspreading to radio transmitting section 218.

Radio transmitting section 218 performs transmission processing such asD/A conversion, amplification and up-conversion on the response signalsubjected to second spreading, and transmits the resulting signal fromantenna 201 to base station 100 (in FIG. 2).

According to the present embodiment, a response signal is subjected totwo-dimensional spreading, by first spreading using a ZC sequence andsecond spreading using a Walsh sequence. That is to say, the presentembodiment spreads a response signal on the cyclic shift axis and on theWalsh axis.

Next, sequence control in control section 209 will be explained indetail.

In code multiplexing by first spreading using a ZC sequence, that is, incode multiplexing on the cyclic shift axis, as described above, asufficient difference is provided between the cyclic shift values of ZCsequences, to an extent that does not cause inter-code interferencebetween the ZC sequences. Therefore, the orthogonality between ZCsequences is little likely to collapse. Also, even if there is a mobilestation that moves fast, the orthogonality between ZC sequences does notcollapse. On the other hand, in code-multiplexing by second spreadingusing a Walsh sequence, that is, in code-multiplexing on the Walsh axis,the orthogonality between Walsh sequences is likely to collapse whenthere is a mobile station that moves fast. Therefore, uponcode-multiplexing response signals by second spreading, it may bepreferable to increase the average multiplexing level on the cyclicshift axis where orthogonality is little likely to collapse, anddecrease the average multiplexing level on the Walsh axis whereorthogonality is likely to collapse. Also, it may be preferable toequalize (unify) the multiplexing level on the Walsh axis between ZCsequences, in order to avoid the situation that, only for the responsesignal subjected to first spreading by a certain ZC sequence, themultiplexing level on the Walsh axis is extremely high. That is, when aresponse signal is subject to two-dimensional spreading on both thecyclic shift axis and the Walsh axis, it may be preferable to reduce theaverage multiplexing level on the Walsh axis and equalize (unify) themultiplexing levels on the Walsh axis between ZC sequences.

That is, the present embodiment controls ZC sequences and Walshsequences based on the associations shown in FIG. 5. That is, controlsection 209 controls the cyclic shift value of a ZC sequence that isused in first spreading in spreading section 214 and a Walsh sequencethat is used in second spreading in spreading section 217 based on theassociations shown in FIG. 5.

Here, in CCE #1 to CCE #18 shown in FIG. 5, probability P to usephysical resources for response signals (i.e. physical resources forPUCCH) associated with the CCE numbers or the priority level of CCE'sdecreases in order from CCE #1, CCE #2, . . . , CCE #17 and CCE #18.That is, in FIG. 5, when the CCE number increases, the above probabilityP monotonically decreases. Therefore, the present embodiment associatesCCE's with ZC sequences and Walsh sequences, as shown in FIG. 5.

That is, referring to the first row (W #1) and second row (W #2) on theWalsh axis in FIG. 5, PUCCH #1 associated with CCE #1 and PUCCH #12associated with CCE #12 are multiplexed, and PUCCH #2 associated withCCE #2 and PUCCH #11 associated with CCE #11 are multiplexed. Therefore,the sum of the CCE numbers of CCE #1 and CCE #12, “13,” is equal to thesum of the CCE numbers of CCE #2 and CCE #11, “13.” That is, on theWalsh axis, CCE's of small numbers and CCE's of large numbers arecombined and allocated. Also, PUCCH #1 and PUCCH #12 are both spread byZC #0, and PUCCH #2 and PUCCH #11 are both spread by ZC #2. The sameapplies to CCE #3 to CCE #10. Further, the same applies to the secondrow (W #1) and third row (W #2) on the Walsh axis. That is, between ZCsequences in FIG. 5, the sum of the CCE numbers of adjacent Walshsequences is equal. In other words, in FIG. 5, the average multiplexinglevels on the Walsh axis are substantially equal (substantially uniform)between ZC sequences.

Thus, the present embodiment associates CCE's (i.e. PUCCH's) withsequences that are used in two-dimensional spreading, based onprobability P to use physical resources for response signals associatedwith the CCE numbers or on the priority level of CCE's. By this means,between ZC sequences, the average multiplexing level on the Walsh axis,that is, the expected values of the number of multiplexed PUCCH's on theWalsh axis are substantially equal (or substantially uniform). Thus,according to the present embodiment, it is less likely that, only for aresponse signal subjected to first spreading by a certain ZC sequence,the multiplexing level on the Walsh axis is extremely high, so that itis possible to minimize the influence when the orthogonality betweenWalsh sequences collapses. Therefore, according to the presentembodiment, it is possible to minimize the degradation of the separationperformance of response signals code-multiplexed by second spreading.

Next, a generation of control information in control informationgenerating section 101 will be explained.

As shown in FIG. 6, control information generating section 101 allocatesL1/L2 CCH's based on the number of CCE's occupied, to reduce the aboveuse probability P when the number of CCE's increases.

FIG. 6 illustrates a case where the coding rate of L1/L2 CCH #1, L1/L2CCH #3 and L1/L2 CCH #4 is 2/3, the coding rate of L1/L2 CCH #2 andL1/L2 CCH #6 is 1/3, and the coding rate of L1/L2 CCH #5 is 1/6.Therefore, the number of CCE's occupied is 1 in L1/L2 CCH #1, L1/L2 CCH#3 and L1/L2 CCH #4, the number of CCE's occupied is 2 in L1/L2 CCH #2and L1/L2 CCH #6, and the number of CCE's occupied is 4 in L1/L2 CCH #5.

That is, control information generating section 101 allocates L1/L2CCH's in order from an L1/L2 CCH of a smaller number of CCE's occupied.In other words, control information generating section 101 allocatesCCE's in order from the CCE of the lowest CCE number, to L1/L2 CCH's inorder from the L1/L2 of the smallest number of CCE's occupied.

Here, as described above, if a plurality of CCE's are allocated to asingle mobile station, the mobile station transmits a response signalusing only the PUCCH associated with the CCE of the minimum number amongthe plurality of CCE's. In other words, if a plurality of CCE's areallocated to a single mobile station, the PUCCH's associated with theCCE's of other numbers than the minimum number among the plurality ofCCE's, are not used and are therefore wasted. That is, if a plurality ofCCE's are allocated to a single mobile station, unused, wasted physicalresources for response signals are provided.

Also, to which mobile station downlink data is transmitted in eachsubframe, is determined based on, for example, the priority level ofdownlink data. Therefore, in a certain subframe, there is a mobilestation to which downlink data is not transmitted. That is, a mobilestation of the transmission destination of downlink data varies betweensubframes in a substantially random manner. Also, if a mobile station ofthe transmission destination of downlink data varies, the coding raterequired in the L1/L2 CCH varies, and, consequently, the number of CCE'sallocated to a single mobile station becomes random between subframes.Similarly, the number of mobile stations that occupy one CCE, the numberof mobile stations that occupy two CCE's and the number of mobilestations that occupy four CCE's becomes random between subframes.

That is, as shown in FIG. 6, in a certain subframe “n,” there are threemobile stations that occupy one CCE, and therefore three PUCCH'sassociated with CCE #1 to CCE #3, respectively, are all used. But, inthe next subframe “n+1,” there may be only one mobile station thatoccupies one CCE. In this case, in subframe n+1, CCE #2 and CCE #3 areallocated to respective single mobile stations, and, consequently, thePUCCH associated with CCE #3 is not used. That is, when the number ofmobile stations that occupy only one CCE is smaller, the use probability(which is averaged over a plurality of subframes) of a PUCCH associatedwith a CCE of a larger CCE number monotonically decreases. That is, whenthe CCE number increases, the above use probability P or the aboveexpected value E monotonically decreases.

Thus, according to the present embodiment, with an assumption that thereare available resources in physical resources for response signals,control information generating section 101 allocates L1/L2 CCH's basedon the number of CCE's occupied, as shown in FIG. 6. By this means, whenthe CCE number increases, it is possible to monotonically decrease theabove use probability P in FIG. 5. That is, the present embodiment usesavailable resources in physical resources for response signals, therebymaking the average multiplexing levels on the Walsh axis substantiallyequal (or substantially uniform).

Thus, according to the present embodiment, control section 209 controlsthe cyclic shift values of the ZC sequence and Walsh sequences based onthe associations shown in FIG. 5, thereby minimizing the degradation ofthe separation performance of response signals code-multiplexed bysecond spreading. Also, control information generating section 101allocates L1/L2 CCH's based on the number of CCE's occupied as shown inFIG. 6, thereby minimizing the waste of physical resources for responsesignals. That is, according to the present embodiment, it is possible tominimize the waste of physical resources for response signals andminimize the degradation of the separation performance of responsesignals code-multiplexed by second spreading.

Embodiment 2

The present embodiment is the same as in Embodiment 1 in allocating anL1/L2 CCH based on the number of CCE's occupied. Here, the presentembodiment differs from Embodiment 1 in using an odd number as theminimum CCE number among the plurality of CCE's when a plurality ofCCE's are allocated to one mobile station.

That is, control information generating section 101 according to thepresent embodiment allocates L1/L2 CCH's as shown in, for example, FIG.7. That is, while, with Embodiment 1 (FIG. 6), L1/L2 CCH #2 occupies CCE#4 and CCE #5, L1/L2 CCH #6 occupies CCE #6 and CCE #7, and L1/L2 CCH #5occupies CCE #8 to CCE #11, with the present embodiment, by not usingCCE #4 as shown in FIG. 7, L1/L2 CCH #2 occupies CCE #5 and CCE #6,L1/L2 CCH #6 occupies CCE #7 and CCE #8, and L1/L2 CCH #5 occupies CCE#9 and CCE #12.

By performing L1/L2 CCH allocation as shown in FIG. 7, mobile stations,to which a plurality of CCE's are allocated, always use physicalresources for response signals associated with odd-numbered CCE's.Therefore, when the CCE number increases, it is possible tosignificantly reduce the above use probability P of physical resourcesfor response signals associated with even-numbered CCE's. That is,according to the present embodiment, it is possible to reduce the aboveuse probability P of physical resources for response signals associatedwith even-numbered CCE's, while increasing the above use probability Pof physical resources for response signals associated with odd-numberedCCE's.

Also, when control information generating section 101 performs L1/L2 CCHallocation as shown in FIG. 7, based on the associations shown in FIG.8, control section 209 controls the cyclic shift value of the ZCsequence used in first spreading in spreading section 214 and the Walshsequence used in second spreading in spreading section 217. In FIG. 8,physical resources for response signals associated with odd-numberedCCE's (with a high use probability P) and physical resources forresponse signals associated with even-numbered CCE's (with a low useprobability P) are allocated on the Walsh axis of the same ZC sequence,respectively. Therefore, referring to the first row (W #0) and thesecond row (W #1) on the Walsh axis shown in FIG. 8, PUCCH #1 associatedwith CCE #1 and PUCCH #12 associated with CCE #12 are multiplexed, andPUCCH #2 associated with CCE #3 and PUCCH #11 associated with CCE #10are multiplexed. Therefore, the sum of the CCE numbers of CCE #1 and CCE#12, “13,” is equal to the sum of the CCE numbers of CCE #3 and CCE #10,“13.” By this means, according to the present embodiment, between ZCsequences, as in Embodiment 1 (FIG. 5), it is possible to substantiallyequalize (unify) the average multiplexing level on the Walsh axis.

Embodiment 3

The present embodiment further takes into account the collapse oforthogonality between ZC sequences on the cyclic shift axis.

If the transmission timing difference in mobile stations, the delay timeof delay waves or frequency offset increases, inter-code interference iscaused between adjacent ZC sequences.

Therefore, with the present embodiment, as shown in FIG. 9, physicalresources for response signals with a high use probability P are notplaced adjacently but are placed in a distributed manner.

That is, for example, referring to the first row (W #0) and the secondrow (W #1) on the Walsh axis shown in FIG. 9, PUCCH #1 associated withCCE #1 and PUCCH #12 associated with CCE #12 are multiplexed, and PUCCH#2 associated with CCE #6 and PUCCH #11 associated with CCE #7 aremultiplexed. Therefore, the sum of the CCE numbers of CCE #1 and CCE#12, “13,” is equal to the sum of the CCE numbers of CCE #6 and CCE #7,“13.” Therefore, according to the present embodiment, as in Embodiment 1(FIG. 5) and Embodiment 2 (FIG. 8), between ZC sequences, it is possibleto substantially equalize (unify) the average multiplexing level on theWalsh axis.

Further, referring to the first column, the third column, the fifthcolumn and the seventh column on the cyclic shift axis (i.e. ZC #0, ZC#2, ZC #4 and ZC #6) in FIG. 9, PUCCH #1 associated with CCE #1, PUCCH#2 associated with CCE #6, PUCCH #3 associated with CCE #2 and PUCCH #4associated with CCE #4 are code-multiplexed using ZC #0, ZC #2, ZC #4and ZC #6 of adjacent cyclic shift values. Therefore, the sum of the CCEnumbers of CCE #1 and CCE #6, “7,” the sum of the CCE numbers of CCE #6and CCE #2, “8,” and the sum of the CCE numbers of CCE #2 and CCE #4,“6,” are substantially equal.

By this means, with the present embodiment, it is possible to reduce thepossibility that a plurality of mobile stations using the same Walshsequence use a plurality of adjacent ZC sequences at the same time.Therefore, with the present embodiment, even in a communicationenvironment in which the orthogonality on the cyclic shift axis is lesslikely to be maintained, it is possible to minimize the degradation ofthe separation performance of response signals.

Embodiment 4

A case will be described with the present embodiment where CCE's areused for both downlink data allocation and uplink data allocation, thatis, where a downlink L1/L2 CCH and an uplink L1/L2 CCH both occupiesCCE's.

In this case, control information generating section 101 may allocateL1/L2 CCH's as shown in FIG. 10 or FIG. 11. That is, as in Embodiment 1(FIG. 6), control information generating section 101 allocates L1/L2CCE's in order from the L1/L2 CCH of the smallest number of CCE'soccupied.

Here, as shown in FIG. 10, control information generating section 101allocates CCE's in order from the CCE of the lowest CCE number, todownlink L1/L2 CCH's in order from the downlink L1/L2 CCH of the lowestchannel number, while allocating CCE's in order from the CCE of thehighest CCE number, to uplink L1/L2 CCH's in order from the uplink L1/L2CCH of the lowest channel number.

Alternatively, as shown in FIG. 11, control information generatingsection 101 allocates CCE's in order from the CCE of the lowest CCEnumber, to uplink L1/L2 CCH's in order from the uplink L1/L2 CCH of thelowest channel number, while allocating CCE's in order from the CCE ofthe highest CCE number, to downlink L1/L2 CCH's in order from thedownlink L1/L2 CCH of the lowest channel number. If the L1/L2 CCHallocation shown in FIG. 11 is performed, based on the associationsshown in FIG. 12, control section 209 controls the cyclic shift value ofthe ZC sequence used in first spreading in spreading section 214 and theWalsh sequence used in second spreading in spreading section 217. InFIG. 12, the above use possibility P or the above priority leveldecreases in order from CCE #18, CCE #17, . . . , CCE #2 and CCE #1.

Therefore, according to the present embodiment, even if CCE's are usedfor both downlink data allocation and uplink data allocation, it ispossible to provide the same effect as in Embodiment 1.

Embodiment 5

A case will be described with the present embodiment where, becausethere is no mobile station that moves fast, inter-code interference ismore likely to occur between ZC sequences than between Walsh sequences.

In this case, referring to only the inter-code interference betweenadjacent ZC sequences on the cyclic shift axis, as shown in FIG. 13, itis preferable to increase the number of response signals multiplexed,preferentially on the Walsh axis at first. By this means, it is possibleto reduce the possibility that a plurality of ZC sequences havingadjacent cyclic shift values are used at the same time. Also, in FIG.13, as in Embodiment 1 (FIG. 5), the above use probability P or theabove priority level decreases in order from CCE #1, CCE #2, . . . , CCE#17 and CCE #18.

Also, if mobile station 200 is the mobile station that performscommunication using VoIP (Voice over Internet Protocol) (i.e. VoIPmobile station), base station 100 periodically transmits downlink datato the VoIP mobile station based on the compression rate of voice data.By this means, studies are underway to report in advance a resourceallocation result of downlink data in a higher layer than the physicallayer, to a VoIP mobile station. That is, control information is nottransmitted to a VoIP mobile station using L1/L2 channels, and,consequently, the VoIP mobile station cannot decide PUCCH's that areused to transmit response signals, from CCE numbers. Therefore, as inthe case of physical resources for data, physical resources for responsesignals that are used in a VoIP mobile station are reported in advancein a higher layer than the physical layer. Therefore, as shown in FIG.14, it may be preferable to allocate physical resources for responsesignals of the low use probability P or the low priority level, to aVoIP mobile station. Also, in FIG. 14, as in Embodiment 1 (FIG. 5), theabove use probability P or the above priority level decreases in orderfrom CCE #1, CCE #2, . . . , CCE #17 and CCE #18. Also, in a frame inwhich a response signal from a VoIP mobile station is assumed totransmit, it may be preferable to use CCE #10 to CCE #18 for reporting aresource allocation result of uplink data or allocate these to an L1/L2CCE that occupies a plurality of CCE's. By this means, it is possible toprevent a collision between a response signal from a VoIP mobile stationand a response signal from a normal mobile station other than the VoIPmobile station.

Embodiment 6

The present embodiment reduces the possibility that the same physicalresources for response signals are used between adjacent cells at thesame time.

When cell #1 and cell #2 are adjacent to each other, ZC sequences andWalsh sequences are controlled in cell #1 based on the associationsshown in the upper of FIG. 15, while ZC sequences and Walsh sequencesare controlled in cell #2 based on the associations shown in the lowerof FIG. 15. Also, in cell #1 and cell #2, L1/L2 CCH allocation isperformed in order from the L1/L2 CCH of the smallest number of CCE'soccupied. In other words, in cell #1 and cell #2, CCE's are allocated inorder from the CCE of the lowest CCE number, to L1/L2 CCH's in orderfrom the L1/L2 CCH of the smallest number of CCE's occupied. Therefore,in CCE #1 to CCE #18 shown in FIG. 15, the above use possibility P orthe above priority level decreases in order from CCE #18, CCE #17, . . ., CCE #2 and CCE #1. That is, for the same physical resources forresponse signals, CCE numbers are associated in one cell so as toincrease the above use probability, while CCE numbers are associated inthe other cell so as to decrease the above use probability. By thismeans, between adjacent cells, it is possible to reduce the probabilitythat ZC sequences of the same cyclic shift value or the same Walshsequences are used at the same time.

Also, if there are physical resources for response signals that are notused in one cell, it is preferable to perform the above associating suchthat the physical resources for response signals that are not used inone cell are preferentially used in the other cell. FIG. 15 illustratesthe case where W #3 is not used in cell #1 and W #0 is not used in cell#2.

Embodiments of the present invention have been explained above.

Also, cases have been described above with the embodiments where threeWalsh sequences of Walsh sequences W #0 to W #2 are used. But, in caseof using two, four or more Walsh sequences, it is equally possible toimplement the present invention in the same way as above. In the case ofusing four or more Walsh sequences, in FIG. 6, FIG. 8 and FIG. 9, theCCE number adding 12 to the CCE number in the n-th column, needs to beallocated to the (n+2)-th column.

Also, the above embodiments show a configuration to compensateinter-code interference between Walsh sequences by the spreading gain ofZC sequence. But, the present invention is applicable not only to caseswhere complete orthogonal sequences such as Walsh sequences are used insecond spreading, but is also applicable to cases where, for example,incomplete orthogonal sequences such as PN sequences are used in secondspreading. In this case, inter-code interference due to the incompleteorthogonality of PN sequences is compensated by the spreading gain of ZCsequence. That is, the present invention is applicable to any radiocommunication apparatuses that use sequences, which can be separatedfrom each other because of different cyclic shift values, for firstspreading and sequences, which can be separated because of differencesof sequences, for second spreading.

Also, cases have been described above with the embodiments where aplurality of response signals from a plurality of mobile stations arecode-multiplexed. But, it is equally possible to implement the presentinvention even when a plurality of reference signals (e.g. pilotsignals) from a plurality of mobile stations are code-multiplexed. Asshown in FIG. 16, when three reference signal symbols R₀, R₁ and R₂, aregenerated from a ZC sequence (having a sequence length of 12), first,the ZC sequence is subjected to an IFFT in association with anorthogonal sequence (F₀, F₁, F₂) having a sequence length of 3. By thisIFFT, it is possible to acquire a ZC sequence having a sequence lengthof 12 in the time domain. Then, the signal subjected to an IFFT isspread using the orthogonal sequence (F₀, F₁, F₂). That is, onereference signal (i.e. ZC sequence) is allocated to three symbols R₀, R₁and R₂. Similarly, other mobile stations allocate one reference signal(i.e. ZC sequence) to three symbols R₀, R₁ and R₂. Here, individualmobile stations use ZC sequences of different cyclic shift values in thetime domain or different Walsh sequences. In this case, the sequencelength of ZC sequences in the time domain is 12, so that it is possibleto use twelve ZC sequences of cyclic shift values “0” to “11,” generatedfrom the same ZC sequence. Also, the sequence length of orthogonalsequences is 3, so that it is possible to use three different orthogonalsequences. Therefore, in an ideal communication environment, it ispossible to code-multiplex maximum thirty-six (12×3) response signalsfrom mobile stations.

Also, a PUCCH used in the above-described embodiments is a channel tofeed back an ACK or NACK, and therefore may be referred to as an“ACK/NACK channel.”

Also, a mobile station may be referred to as “UE,” a base station may bereferred to as “Node B,” and a subcarrier may be referred to as a“tone.” Also, a CP may be referred to as a “GI (Guard Interval).”

Also, the method of detecting an error is not limited to a CRC.

Also, a method of performing transformation between the frequency domainand the time domain is not limited to IFFT and FFT.

Also, a case has been described with the above-described embodimentswhere the present invention is applied to mobile stations. But, thepresent invention is also applicable to a fixed radio communicationterminal apparatus in a stationary state and a radio communication relaystation apparatus that performs the same operations with a base stationas a mobile station. That is, the present invention is applicable to allradio communication apparatuses.

Although a case has been described with the above embodiments as anexample where the present invention is implemented with hardware, thepresent invention can be implemented with software.

Furthermore, each function block employed in the description of each ofthe aforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of an FPGA (FieldProgrammable Gate Array) or a reconfigurable processor where connectionsand settings of circuit cells in an LSI can be reconfigured is alsopossible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosure of Japanese Patent Application No. 2007-161969, filed onJun. 19, 2007, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The present invention is applicable to, for example, mobilecommunication systems.

1. A base station apparatus comprising: a transmitting unit configuredto transmit data to a radio communication apparatus, and transmit, tothe radio communication apparatus, control information on one or aplurality of control channel elements (CCEs) with consecutive CCEnumber(s), CCEs being numbered sequentially from one; and a receivingunit configured to receive a response signal corresponding to the data,the response signal being transmitted from the radio communicationapparatus, wherein: the response signal is spread with a sequencedefined by a cyclic shift value, which is determined among a pluralityof cyclic shift values from a resource associated with a first CCEnumber of said one or a plurality of CCEs, and with an orthogonalsequence, which is determined among a plurality of orthogonal sequencesfrom said resource; and different cyclic shift values used for the sameorthogonal sequence are respectively determined from a resourceassociated with an odd CCE number and a resource associated with an evenCCE number, and the first CCE number is restricted to be an odd numberwhen the control information is transmitted on the plurality of CCEs. 2.The base station apparatus according to claim 1, further comprising adespreading unit configured to despread the response signal.
 3. The basestation apparatus according to claim 1, wherein two of the cyclic shiftvalues, which are used for the same orthogonal sequence and which areadjacent to each other with a predefined interval, are respectivelydetermined from a resource associated with an odd CCE number and aresource associated with an even CCE number.
 4. The base stationapparatus according to claim 1, wherein the first CCE number is notrestricted to be either an odd number or an even number when the controlinformation is transmitted on one CCE.
 5. The base station apparatusaccording to claim 1, wherein: the resource is used for transmission ofthe response signal; and the first CCE number, with which the resourcethat is used only when the control information is transmitted on one CCEis associated, is restricted to be an even number.
 6. The base stationapparatus according to claim 1, wherein: the resource is used fortransmission of the response signal; and probabilities to be used aredifferent between the resource associated with an odd CCE number and theresource associated with an even CCE number.
 7. The base stationapparatus according to claim 1, wherein: a resource index of theresource is consecutively associated with the CCE number; and the cyclicshift values, which are used for the same orthogonal sequence, arerespectively determined from the resource indices which are consecutivein a direction in which the cyclic shift value is shifted.
 8. The basestation apparatus according to claim 1, wherein: a sequence having alength 12 is used as the sequence defined by the cyclic shift value; anda sequence having a length 4 is used as the orthogonal sequence.
 9. Thebase station apparatus according to claim 1, wherein the response signalis a response signal of ACK or NACK.
 10. A base station apparatuscomprising: a transmitting unit configured to transmit data to a radiocommunication apparatus, and transmit, to the radio communicationapparatus, control information on one or a plurality of control channelelements (CCEs) with consecutive CCE number(s); and a receiving unitconfigured to receive a response signal corresponding to the data, theresponse signal being transmitted from the radio communicationapparatus, wherein: the response signal is spread with a sequencedefined by a cyclic shift value, which is determined among a pluralityof cyclic shift values from a resource associated with a first CCEnumber of said one or a plurality of CCEs, and with an orthogonalsequence, which is determined among a plurality of orthogonal sequencesfrom said resource; the resource is used for transmission of theresponse signal; and different cyclic shift values used for the sameorthogonal sequence are respectively determined from a resource, whichis used when the control information is transmitted on the plurality ofCCEs, and a resource, which is used when the control information istransmitted on one CCE.
 11. The base station apparatus according toclaim 10, wherein two of the cyclic shift values, which are used for thesame orthogonal sequence and which are adjacent to each other with apredefined interval, are respectively determined from a resource, whichis used when the control information is transmitted on the plurality ofCCEs, and a resource, which is used when the control information istransmitted on one CCE.
 12. The base station apparatus according toclaim 10, wherein: CCEs are numbered sequentially from one, and thefirst CCE number is restricted to be an odd number when the controlinformation is transmitted on the plurality of CCEs.
 13. The basestation apparatus according to claim 10, wherein CCEs are numberedsequentially from one, the first CCE number is restricted to be an oddnumber when the control information is transmitted on the plurality ofCCEs, and the first CCE number is not restricted to be either an oddnumber or an even number when the control information is transmitted onone CCE.
 14. The base station apparatus according to claim 10, whereinCCEs are numbered sequentially from one, the first CCE number isrestricted to be an odd number when the control information istransmitted on the plurality of CCEs, and the first CCE number, withwhich the resource that is used only when the control information istransmitted on one CCE is associated, is restricted to be an evennumber.
 15. A response signal receiving method comprising: transmittingdata to a radio communication apparatus; transmitting, to the radiocommunication apparatus, control information on one or a plurality ofcontrol channel elements (CCEs) with consecutive CCE number(s), CCEsbeing numbered sequentially from one; and receiving a response signalcorresponding to the data, the response signal being transmitted fromthe radio communication apparatus, wherein: the response signal isspread with a sequence defined by a cyclic shift value, which isdetermined among a plurality of cyclic shift values from a resourceassociated with a first CCE number of said one or a plurality of CCEs,and with an orthogonal sequence, which is determined among a pluralityof orthogonal sequences from said resource; and different cyclic shiftvalues used for the same orthogonal sequence are respectively determinedfrom a resource associated with an odd CCE number and a resourceassociated with an even CCE number, and the first CCE number isrestricted to be an odd number when the control information istransmitted on the plurality of CCEs.